Improvement in rocking standards for dental engines



E. T. STARR. Rocking-Standard for Dental-Engines.

N0.,1991,477. Patented Jan. 22,1878.

WITNESSE/s' l INVEJVTOR -WQW QM www SM UNITED STATES PATENT FIICE.

ELI T. STARR, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO SAMUEL S.WHITE, OF SAME PLACE.

IMPROVEMENT IN ROCKING STANDARDS FOR DENTAL ENGINES.

Specification forming part of Letters Patent No. 199,477, dated January22, 1878; application iled December 21, 1877.

To all. whom 'it may concer/n:

Be it known that I, ELI T. STARR, of the city and county ofPhiladelphia, in the State eof Pennsylvania, have invented certain newand useful Improvements in Rocking Standards for Dental Engines, ofwhich the following is a specification:

My invention constitutes an improvement upon the rocking standard of theWell-known S. S. White dental engine, in which the driving-shaft ismounted on a standard rocking on its supporting-base. The lower end ofthis standard extends below the pivot on which it rocks, and is providedwith a spiral spring to maintain the standard normally in an uprightposition, While permitting it to yield to enable the operator to varythe. position of the handpiece. Owing to the construction of thisspring, its resistance increases rapidly as the standard is deiiectedfrom a vertical position, and this constantly-increasing strain tends toannoy and'embarrass the operator while Working.

The object of my invention is to obviate this difficulty, which end Iattain by substituting for the spiral spring above mentioned aplatespring, rigidly secured at one end to the base of the engine, whilethe other end bears against the rocking standard, and tends to maintainit in its upright position.

In the accompanying drawings, Figure l shows a side view, and Fig. 2 anend view, of a dental-engine standard, with my improvements appliedthereto.

The frame A rocks on a fulcrum, a., on the base B, in the usual way. Aplate-spring, C, rigidly secured to the standard or base at c, extendsupward a sufficient distance to overlap the extension A of the rockingarm, passing through a loop, al, on said extension, in which is mounteda friction-roller, c2. This spring, it will be observed, is so arrangedthat the arm can only rock in one direction-that is, toward theoperator-as it forms a lock against the movement of the rocking armbeyond its normal position in the other direction.

the operation of the devices is such that if the movement be continuedto a certain point the arm would remain locked, while, if carried beyondthat point, the tendency of the arm would be to slip 0E from the end. ofthe spring.

To prevent this, I form a hook, c', on the outer end of the spring,which limits the range of movement ofthe rocking arm.

The advantages of my improvements will be obvious to those skilled inthelart without fur- A ther explanation.

I claim as my inventionl. The combination, substantially as hereinbeforeset forth, of a base or supporting-standard, a rocking arm pivotedthereon, and aplate-spring fixed upon the base and acting upon therocking-arm, whereby the tension of the spring diminishes as the arm isdeflected.

2. The combination, substantially as hereinbefore set forth, of thebase, the rocking arm pivoted thereon, and the spring secured to thebase overlapping the extension of the arm and moving endwise throughaloop thereon, whereby the spring acts as a lock to prevent the movementof the rocking arm in one direction.

3. The plate-spring, secured at one end to the base, provided with ahook at the other, and movable endwise through a loop on an extension ofthe rocking arm to limit the range of movement of the latter.

In testimony whereof I have hereunto suloscribed my name.

ELI T. STARR.

Witnesses WM. D. BALDWIN, WM. J. PEYroN.

